There are no known therapeutic agents, either prophylactic (before
the individual contacts the disease, to prevent infection) or
therapeutic (to control or eliminate the disease in an infected
animal).

Some genetic factors have been shown to affect the susceptibility of
individuals to TSE diseases or the incubation time following exposure to
the TSE agents. In domestic animals it has been suggested that it may be
possible to breed for resistance to TSEs, removing TSE-susceptible
genotypes from the gene pool. However breeding for resistance
is not a practical proposition for free-living animals. Based on genetic
studies carried out to date, the majority of deer and elk in
CWD-positive areas appear to be susceptible to CWD.

Vaccination is
commonly used in the prevention and control of infectious diseases in
captive populations. However the use of vaccines to prevent infection in
free-living populations of animals is more problematic, due to
difficulties in delivering the vaccine to the individuals. (B127.13.w13)

Where vaccination is used for the purpose of reducing transmission
of a disease within a population (as with vaccination campaigns
against rabies in wild carnivores), a minimum number or proportion of
the population must be protected by the vaccine if the strategy is to
be effective. The proportion which must be protected may be determined
by considering the population biology of the disease. (B127.13.w13)

In the case of CWD vaccination cannot be used in either captive
cervids or free-living populations as there are, at least at the
present time, no vaccines available [2002]. (J40.66.w1,
P10.67.w1,
N8.18.w8,
D119).

Genetic manipulation of free-ranging deer is extremely
difficult and is not a
practical management option for the control of CWD.

It is recognised that a few individuals in research
facilities with endemic CWD did not develop CWD during their lifetime,
but the reasons for this, genetic or otherwise, are not known. (J40.66.w1)

Work to date in Cervus elaphus nelsoni - Rocky Mountain Elk (Cervus
elaphus - Red deer) suggests that genotype
may affect the susceptibility
of this species to
CWD. However the most common genotypes in the population
were shown to be susceptible to CWD.

Cervus elaphus nelsoni - Rocky Mountain Elk (Cervus
elaphus - Red deer) have a polymorphism (Met/Leu) at cervid codon
132. In one study Met/Met homozygotes were over-represented among
CWD-positive animals and no Leu/Leu animals were CWD-positive.
However only a few Leu/Leu animals were tested so it could not be
stated that this definitely showed resistance of the Leu/Leu genotype individuals. The commonest CWD-positive genotype (Met/Met)
was also the commonest
genotype in the population (75.1 % of the
wild population); Leu/Leu homozygotes made up only 1.1% of the
population.(J223.80.w1)

Resistant genotypes, if present, will not, over any
reasonable time span, become most common in the population, because the
disease usually appears well after individuals have reached breeding
age. Therefore susceptible genes would already have been passed to the
next generation before an individual became clinically ill due to CWD.

"If it exists, genetic resistance might
spare individuals in wild populations, but it is unclear that it
would have a significant protective value at the population level,
at least in the short term." (D109.w5)

Controlling of breeding in free-ranging deer is not
practical.

The situation is different from that with scrapie in
domestic sheep. In domestic sheep, although as with deer and CWD,
reproduction may have occurred before the individual shows clinical
signs, it is possible for a farmer to remove from the herd both the
clinically affected individual and its offspring (D109.w5).
This may be possible in farmed cervids but would not be possible in
free-living individuals.

It has been suggested that some deer
may possess a genetic resistance to CWD and that the fatal brain
disease could be controlled by genetically improving the deer herd.
Others have suggested that genetically engineering a CWD resistant
deer may be possible. Current scientific evidence indicates that the
vast majority of white-tailed deer are likely susceptible to CWD, and
there is no evidence confirming genetic resistance in this species.
While a genetic strategy may appear theoretically viable, there is no
practical evidence to suggest that free-ranging deer could be
manipulated by genetic engineering, artificial breeding, or
propagation and release of animals in order to produced a genetically
resistant population. Considering the long course of disease in deer,
the high annual reproductive potential of females, and the limited
ability to control breeding in free-ranging deer, strategies to
manipulate genetic resistance of whitetailed deer to CWD is not
currently practical. (D109.w3)
Environmental Impact Statement; On Rules to Eradicate Chronic Wasting Disease from Wisconsin's Free-Ranging White-tailed Deer Herd